1. Field of the Invention
The present invention relates to a rack bush and a rack pinion type steering apparatus having the rack bush for a vehicle. More particularly, the present invention relates to a rack bush and a rack pinion type steering apparatus having the rack bush for a vehicle, which can smoothly support a load in an axial direction and a vertical direction of a rack bar so that it is possible to reduce abnormal abrasion of the rack bush, reduce a rattle noise caused by external force transferred through the rack bar during movement of the rack bar, and prevent damage to the rack bar and a pinion through distribution of the load due to an external impact on the shaft.
2. Description of the Prior Art
A steering apparatus is generally equipped between a driver's seat and wheels for moving the wheels by a driver. The steering apparatus includes a steering shaft located in a lower side of the steering wheel of the driver's seat, a gear box connected with the steering shaft, and a rack bar connected to wheels while extending in a left and right direction so as to directly operate the wheels according to an operation of the gear box.
FIG. 1 is a partial cross-sectional view illustrating a rack pinion type steering apparatus for a vehicle according to a prior art.
As illustrated in FIG. 1, a gear box 125 that is connected with a rack housing 137 in a side direction is provided at a lower side of a steering wheel 110 and a steering shaft 115.
The gear box 125 includes an input shaft 120 on an internal upper side of the gear box 125, in which the input shaft 120 is connected to the steering shaft 115 to receive rotational force generated in the steering wheel 110.
The gear box 125 includes a pinion (not shown) provided at an internal lower side of the gear box 125, in which the pinion (not shown) rotates by the rotational force transferred through the input shaft 120 and has teeth in an outer peripheral portion of its end. Further, the gear box 125 includes the rack housing 137 at a lower outer side of the gear box 125, in which the rack housing 137 is integrally formed with the gear box 125 and extending in both side directions.
The rack housing 137 is a hollow pipe and has opened entrances in both sides. Further, the rack housing 137 includes a rack bush 160 and a rack stopper 165 at one side of the opened entrance and a bellows 150 at an outer peripheral side of the rack housing 137.
The rack housing 137 includes a rack bar 140 having a rack at a center of the rack bar 140 in an inner side of the rack housing 137, so that the rack bar 140 can be teeth-assembled with a pinion formed in the gear box 125.
The rack bar 140 linearly moves in an axial direction in an inner side of the rack housing 137, and includes a rack at a center of the rack bar 140 so that the rack bar 140 can be teeth-assembled with the pinion of the gear box 125. A left side and a right side of the rack bar 140 is connected with a tie rod 155 through an inner ball joint of which a ball is inserted into and assembled with a ball housing 175, thereby steering the wheels.
In the meantime, the rack bush 160 is provided at one opened side of the rack housing 137 so as to support the rack bar 140 and guide the movement of the rack bar 140.
The rack bush 160 is shaped like a hollow pipe, of which an outer peripheral surface is in contact with and fixed to an inner peripheral surface and a stepped portion 135 of the rack housing 137 and an inner peripheral surface is in contact with an outer peripheral surface of the inserted rack bar 140, to guide the sliding of the rack bar 140. A rack stopper 165 is pressed into the rack housing 137 at the other end of the rack bush 160.
That is, the rack stopper 165 is installed at the end of the rack bush 160, in which the rack stopper 165 shaped like a hollow pipe is in contact with the rack bush 160 so as to seal the rack housing 137 and fixed to the inner peripheral surface of the rack housing 137, thereby preventing the rack bush 160 from being separated.
The rack bush and the rack pinion type steering apparatus having the rack bush for a vehicle according to the prior art has a problem in that the load in an axial direction and a vertical direction of the rack bar is transferred to the rack bush through the rack bar, the rack bush, and the rack housing during the steering of the steering wheel of the driver, so that abnormal abrasion and noise in the rack bush are generated.
Further, the rack bush fails to smoothly support the load in an axial direction and a vertical direction of the rack bar so that the rack bar and the pinion shaft are damaged due to the impact transferred from the outside through a road surface.